The Disruptor is a "project" that Topher had been working on as a means of preventing incidents like the Alpha composite event. The device produces a pulse that makes an active fall unconscious. Originally the Disruptor was parabolic, and incapacitated any active in a 50' radius, but after some modifications it acted as a "taser" (as Bennett Halverson described it) so it worked in a straight line. (S2: "The Public Eye", "The Left Hand")
Though the Disruptor should work on anyone who has not been imprinted with the Dollhouse's Active architecture, it can have an effect on former dolls; when Paul Ballard attempted to use it on Cindy Perrin, in the mistaken belief that she was a sleeper active programmed to assassinate Madeline Costley, it instead knocked out Madeline. (S2: "The Public Eye")
Topher later refined this technology and created a gun-like device which could wipe an active at a distance, as well as a prototype of a device that could remotely wipe and imprint anyone, not just Actives. (S2: "Meet Jane Doe", "A Love Supreme")